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<title>Debugging with GDB: Value Sizes</title>

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<a name="Value-Sizes"></a>
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<a name="Value-Sizes-1"></a>
<h3 class="section">10.23 Value Sizes</h3>

<p>Whenever <small>GDB</small> prints a value memory will be allocated within
<small>GDB</small> to hold the contents of the value.  It is possible in
some languages with dynamic typing systems, that an invalid program
may indicate a value that is incorrectly large, this in turn may cause
<small>GDB</small> to try and allocate an overly large ammount of memory.
</p>
<dl compact="compact">
<dd><a name="index-set-max_002dvalue_002dsize"></a>
</dd>
<dt><code>set max-value-size <var>bytes</var></code></dt>
<dt><code>set max-value-size unlimited</code></dt>
<dd><p>Set the maximum size of memory that <small>GDB</small> will allocate for the
contents of a value to <var>bytes</var>, trying to display a value that
requires more memory than that will result in an error.
</p>
<p>Setting this variable does not effect values that have already been
allocated within <small>GDB</small>, only future allocations.
</p>
<p>There&rsquo;s a minimum size that <code>max-value-size</code> can be set to in
order that <small>GDB</small> can still operate correctly, this minimum is
currently 16 bytes.
</p>
<p>The limit applies to the results of some subexpressions as well as to
complete expressions.  For example, an expression denoting a simple
integer component, such as <code>x.y.z</code>, may fail if the size of
<var>x.y</var> is dynamic and exceeds <var>bytes</var>.  On the other hand,
<small>GDB</small> is sometimes clever; the expression <code>A[i]</code>, where
<var>A</var> is an array variable with non-constant size, will generally
succeed regardless of the bounds on <var>A</var>, as long as the component
size is less than <var>bytes</var>.
</p>
<p>The default value of <code>max-value-size</code> is currently 64k.
</p>
<a name="index-show-max_002dvalue_002dsize"></a>
</dd>
<dt><code>show max-value-size</code></dt>
<dd><p>Show the maximum size of memory, in bytes, that <small>GDB</small> will
allocate for the contents of a value.
</p></dd>
</dl>




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